Letch,
I wouldnt imagine that theres a large difference in sonic quality between the platters used on the Teres 255 versus the one used on the 265, but you will need to ask Doug for more information. I think its more a matter of aesthetics than sound. I prefer the look of acrylic on wood, rather than wood on wood. But thats me.
While you know I like the Teres 255, please keep in mind that you will have to do some finishing work, and you will need to feel fairly comfortable with that decision. I am sure that more than a couple of hours are required despite what is said on the Teres web sit. But if the process does not intimidate you, by all means go for it!
If I were to buy the Galibier, I would choose the upgrade platter, especially after reading Twls comments above about rotational momentum reducing stylus drag. I think thats important. However, the PVC platter does not appeal to me from an aesthetics point of view. Sure PVC might be heavier, but I like the look of acrylic much better.
I dont know what you have read about acrylic platters, but there seems to be many turntables that use acrylic for their platters including Clearaudio, Transrotor, and Bluenote, just to name three. And if you go with the lead-shot version, you will be buying a platter with a lot more mass, which should help reduce the upper-midrange resonance that Twl talked about. I am also wondering what a platter mat might do as well?
Let me know about your listening impressions after you have heard the Teres. I wont get that opportunity before I buy.